Fly half Ben Botica, who qualifies to play for England next year, has also agreed a new three-year contract as he shapes up as current number 10 Nick Evans' understudy and long-term successor.

London Irish winger Marland Yarde sealed a money spinning switch to Quins last month, while academy graduates Tom Guest and Sam Smith have agreed moves away from the former Premiership champions in recent weeks.

England triumphed 13-10 over Ireland in the Six Nations on Saturday with a try that could easily have graced the Stoop as Danny Care profited from a break from Mike Brown, who had - in turn - been set free by skipper Chris Robshaw.

And Ellis revealed using the increased salary cap to secure the long-term futures of the club's current senior England contingent and its rising stars was more important than bringing in fresh faces.

"This is our golden period. Statistically we have won more percentage of games than we ever have," he said.

"Look at the strength in depth we have. We have 11 Elite Player Squad players and three captains of England in our squad.

"There are times we could have played better this season - we all acknowledge that - and other times when games could have gone either way.

"We have come a long way. No other Premiership club has held the number of trophies at any one time than we have. These are unprecedented times for us.

"Our biggest problem is keeping the players we have. We think we have one of the best squads. The challenge is they are just getting better and better.

"As they grow and mature the problem is going to be holding on to that talent.

"Some young players - because of the injuries - have already come into big games, like Charlie Walker. They are going to get better and better, quicker and quicker."

Buchanan, Gray, Matthews and Ward have all appeared in an England Saxons jersey in recent seasons, while Botica was instrumental in the club’s LV= Cup and A League successes last season and has scored 276 points in 46 appearances.

And O'Shea, who himself signed a new contract last year, admitted securing their services was key to his plans.

"We are obviously delighted that these players have committed to us and will continue their development at Harlequins," said O'Shea.

"They are here to win trophies but they also understand that if the group succeeds then they will be in a position to achieve their personal aims.

"As much as we are able to, we want to keep the core of our group together for as long as possible and their commitment really allows us to push on and plan for the future."